(07.01 MC) The concentration of a medication M in mg/L prese…

(07.01 MC) The concentration of a medication M in mg/L present in the bloodstream decreases over time such that the concentration of medication is proportional to the amount of medication t hours after the first dose. The concentration of medication 30 minutes after the first dose is 40 mg/L and was decreasing at a rate of 50 mg/L per hour. Which differential equation represents this relationship?